add Go's ServeMux Request.PathValue access semantics to Exchange, Mux and MuxSlice

http/httpraw/form.go

@@ -22,6 +22,9 @@ func (f *Form) Reset(buf []byte, capKV int) {
 // ParseBytes copies the argument bytes to the Form's underlying buffer and parses them.
 func (f *Form) ParseBytes(b []byte) error {
 	f.Reset(nil, 0)
+	if len(b) == 0 {
+		return nil // An empty body is an empty form, not a failure to read one.
+	}
 	err := f.kv.ReadFromBytes(b)
 	if err != nil {
 		return err
@@ -54,7 +57,7 @@ func (f *Form) Decode() error {
 			return err
 		} else if len(v) == 0 {
 			if nk != len(k) {
-				f.kv.setAt(i, k, v)
+				f.kv.setAt(i, k[:nk], v) // k[:nk]: the decoded key is shorter.
 			}
 			continue
 		}

http/httpraw/form_test.go

@@ -66,6 +66,29 @@ func TestFormDecode(t *testing.T) {
 	}
 }
 
+// Decoding a valueless key that shrinks must rewrite the key without inventing
+// a value: the pair has no '=' before Decode and must have none after.
+func TestFormDecodeValuelessKeyShrinks(t *testing.T) {
+	var f Form
+	const body = "a=1&o%6Bay"
+	if err := f.ParseBytes([]byte(body)); err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Decode(); err != nil {
+		t.Fatal(err)
+	}
+	const want = "a=1|okay"
+	if got := render(&f); got != want {
+		t.Errorf("want %q, got %q", want, got)
+	}
+	if _, value := f.Pair(1); value != nil {
+		t.Errorf("want valueless pair to stay valueless, got value %q", value)
+	}
+	if !f.Has("okay") {
+		t.Error("want decoded valueless key present")
+	}
+}
+
 // A malformed escape must be reported, never silently passed through.
 func TestFormDecodeMalformed(t *testing.T) {
 	for _, body := range []string{"q=%zz", "%zz=v", "q=%4"} {

http/httpraw/header.go

@@ -241,49 +241,11 @@ func (h *Header) SetInt(key string, value int64, base int) {
 // Calling Set mangles the buffer.
 func (h *Header) Set(key, value string) (enoughSpace bool) {
 	return h.hbuf.kv.Set(key, value)
-
-	// useKv := h.takeReusableSlot(key)
-	// if useKv == nil {
-	// 	h.hbuf.kv.appendPair(key, value)
-	// } else {
-	// 	useKv.value = h.hbuf.kv.reuseOrAppend(useKv.value, value)
-	// }
-}
-
-// takeReusableSlot returns the valid key-value entry for key with the largest
-// value buffer (best candidate for in-place reuse) and invalidates any other
-// entries sharing the key. Returns nil if the key is not present.
-func (h *Header) takeReusableSlot(key string) *argsKV {
-	// hb := &h.hbuf
-	var useKv *argsKV
-	// for i := 0; i < len(hb.headers); i++ {
-	// 	// Search for key-value with largest buffer for value to store value reusing buffer.
-	// 	gotkv := &hb.headers[i]
-	// 	if gotkv.isValidHeader() && b2s(hb.musttoken(gotkv.key)) == key {
-	// 		if useKv == nil {
-	// 			useKv = gotkv
-	// 		} else if gotkv.value.len > useKv.value.len {
-	// 			useKv.invalidate()
-	// 			useKv = gotkv
-	// 		} else {
-	// 			gotkv.invalidate()
-	// 		}
-	// 	}
-	// }
-	return useKv
 }
 
 // Get gets the first exact-match value of a key found in the headers. Use [Header.ForEach] to find multiple values corresponding to same key.
 func (h *Header) Get(key string) []byte {
 	return h.hbuf.kv.Get(key)
-	// debuglog("http:get:start")
-	// kv := h.peekHeader(key)
-	// if kv.isValidHeader() {
-	// 	debuglog("http:get:found")
-	// 	return h.hbuf.musttoken(kv.value)
-	// }
-	// debuglog("http:get:notfound")
-	// return nil
 }
 
 // GetFold gets the first value whose key matches key under ASCII case-insensitive

http/httpraw/kvbuffer.go

@@ -225,9 +225,11 @@ func (mb *KVBuffer) At(i int) (key, value []byte) {
 }
 func (mb *KVBuffer) setAt(i int, k, v []byte) {
 	mb.flags |= flagMangledBuffer
+	// Route through slice, not bytes2tok: a nil v is a pair with no '=' and must
+	// stay absent rather than trip the alias check on a nil pointer.
 	mb.kvs[i] = argsKV{
-		key:   bytes2tok(mb.buf, k),
-		value: bytes2tok(mb.buf, v),
+		key:   mb.slice(k),
+		value: mb.slice(v),
 	}
 }
 

http/httpraw/parse.go

@@ -12,10 +12,10 @@ var (
 	errNoProto = errors.New("missing protocol, HTTP/0.9 unsupported")
 	// ErrNeedMoreData signals a parser was handed an incomplete buffer: append
 	// more data to it and call again.
-	ErrNeedMoreData      = errors.New("need more data: cannot find trailing lf/delimiter")
-	errNoBoundary        = errors.New("httpraw: multipart boundary not set")
-	errUnparsed          = errors.New("need to finish parsing")
-	errInvalidName       = errors.New("invalid header name")
+	ErrNeedMoreData = errors.New("need more data: cannot find trailing lf/delimiter")
+	errNoBoundary   = errors.New("httpraw: multipart boundary not set")
+	errUnparsed     = errors.New("need to finish parsing")
+	errInvalidName  = errors.New("invalid header name")
 	// ErrBufferExhausted signals a buffer with no room left for the data being
 	// written and no permission to grow, see [KVBuffer.EnableBufferGrowth].
 	// Enlarging the buffer handed to Reset is the only fix; a server answers it